For the past years, various methods of dyeing hair have been known in the art. In one of the conventional methods, oxidation dyes are permeated into hair in an alkaline condition, treated with oxidizing agents such as hydrogen peroxide or the like and then are polymerized within the hair for developing color. Alternatively, acid dyes are permeated into the hair for dyeing. There is also another temporary coloring method in which coloring matter or pigment is adhered or fixed to hair using binders for developing colors.
However, those methods are known to have various disadvantages. For example, oxidation dyes pose problems such as damaged hair due to dyeing treatment, allergic effects and irritation to skin, especially to mucus and eye. Although less irritating to skin, the acid dyes are often not satisfactory in finish and disadvantageous in losing color when hair is washed. Skin is sometimes stained by dyes when hair is dyed. The temporary coloring method does not provide a good tactile property because of stickiness, brittleness or the like of applied binders. In addition, resistance to abrasion is generally not sufficient in this method.
Recently, antibodies have been used as cosmetics. For example, Japanese Laid-open Patent Application No. 4-29912 discloses a method in which antibodies are modified with functional molecules of dyes, perfumes, humectants and the like, and then said functional molecules are transferred together with the antibodies to the desired place on account of the specificity of the antibodies.
However, no testing is described about hair dyes in the above patent application though there is a description to the effect that an antibody modified with phycopyrine protein (a fluorescent substance corresponding to a water-soluble natural dye) was applied to skin in an example of the above patent. In addition, according to the above-mentioned method, there exist such problems that sufficient amounts of dyes required to color hair are hardly immobilized on the antibody and that too much load of the dyes may inactivate the antibody. Thus, this method cannot be put into practice.
On the other hand, a method has been known in which antibody-modified pigments are used as diagnostic reagents. However, in this method the pigments are used as a label only for the purpose of the temporary confirmation of the existence of targeted substances, and are not intended to color the targeted substances as dyes. Accordingly, no significant investigations have been conducted on coloring efficiency and color durability (coloring strength) as dyes.